Responses Of Chemical Properties Of Soil And Litter Of Eucalyptus Plantations In Simulated Acid Deposition

Eucalyptus is one of the three fast-growing species in the tropics.The main producing areas of Guangxi's Eucalyptus are located in the acid rain-prone areas.Acid rain exacerbates soil acidification,resulting in leaching of soil nutrients,affecting the growth of trees.In this paper,the soil pH value and exchangeable Al content,soil N and P content and soil exchangeable salt content were studied by simulating acid deposition on the soil and litter of Eucalyptus plantation.The effects of pH value on nutrient,soil enzyme activity,leaf litter nutrient and litter eluent nutrient concentration under acid deposition were studied.The effects of simulated acid deposition on the soil and the soil litter,the results are as follows:1.The soil pH value of two forest was significantly decreased at pH3.0,pH4.0 treatment.Eucalyptus pure forest soil exchangeable Al is more sensitive to acid deposition,it is easy to leach in the pH3.0,pH4.0 treatment,so it produces low toxicity of Al.2.The contents of total N in the soil of Eucalyptus were increased,while the content of ammonium N was significantly decreased.The contents of nitrate N in soil of two forest was significantly decreased under pH3.0 treatment.The contents of total P in the soil were a lot leaching under the treatment of pH4.0,and the two soils were leached at pH3.0 and pH4.0.In the acid rain area to create Eucalyptus and Castanopsis mixed forest about P element is better than Eucalyptus pure forest.3.The exchangeable K,exchangeable Mg,exchangeable Ca and exchangeable Na contents of Eucalyptus plantations under simulated acid deposition showed significant leaching characteristics.There was a significant negative correlation between K,exchangeable Mg,exchangeable Ca,exchangeable Na and soil total N.4.The pH value of the soil eluent is significantly reduced under acid deposition.Eucalyptus pure forest soils have strong buffering capacity for acid deposition.The contents of total N,total P,total K,total Mg and total Ca in the soil eluent were significantly higher in acid treatment than those in the other treatments.The soil nutrient of the two stands was leached under acid treatment.5.Soil catalase,soil sucrase,soil urease and soil protease activity were significantly decreased at pH3.0 and pH4.0 treatments.There was a significant positive correlation between soil enzyme activity and soil N and available P contents in the Eucalyptus plantation,while the soil enzyme activity of Eucalyptus and Castanopsis mixed forest was positively correlated with soil N content.The soil enzyme activity was also higher when soil N content was higher.6.Leaf litter nutrient content at pH3.0 and pH4.0 treatments was significantly higher than pH5.6 treatments and CK.Leaf litter eluent nutrient content at pH3.0 and pH4.0 treatments was significantly lower than pH5.6 treatments and CK.There was a significant negative correlation between the nutrient content of litter and the nutrient content of litter eluent,which was significantly or negatively correlated with the pH value of the eluent.The nutrient content of the litter eluent was significantly higher than that of the eluent very significant positive correlation.Acid deposition reduces the nutrient of leaf litter into the soil,while it leaves the soil exchangeable salt away from a lot of leaching,and further cause soil nutrient deficiencies.